Vinyl polymers plasticized with airblown extracts of mineral oil fractions



Patented May 24, 1949 VINYL POLYMERS PLASTICIZED WITH AIR- BLOWNFRACTIONS EXTRACTS OF MINERAL OIL Eric William Musther Fawcett, EricSylvester Narracott, and Kathleen Joan Rowland, Sunbury-on-Thames,England, assignors to Anglo- Iranian Oil Company Limited, London,England, a British joint-stock corporation No Drawing. ApplicationDecember 22, 1944, Se-

rial No. 569,418. In Great Britain December The invention relates to theproduction of a plasticised polyvinyl halide such as vinyl chloride orpolyvinyl halide co-polymers such as polyvinyl chloride with co-polymersof vinyl acetate, methyl acrylate, vinylidene chloride or the like,adapted for use for example as coating compositions, cable dielectriccompounds, and moulding compositions.

The use of substances of the character of tricresyl phosphate, dibutylphthalate and dibenzyl sebacate as plasticisers for polyvinyl chlorideor its co-polymers has long been practised. They are polar in character,and are thus known to have an adverse efiect on the electrical and waterresistant properties of the polymers. Their other physical properties,such for example as tensile strength are also known to depreciaterapidly with increasing additions of the plasticisers to these polymers.

In the specification filed pursuant to the application Serial No.513,468, filed Dec. 8, 1943, a process is described for producing suchcompositions in the use as plasticisers or partial plasticisers, and/ orfillers, of certain hydrocarbonsobtained from mineral oil fractions byextraction with selective solvents of a polar character. Thesehydrocarbons are of molecular weight preferably within the range 250-750and their initial and final boilingpoints are in the range 250-800 C. at760 mm. Hg pressure. The preferred hydrocarbons are characterised by ahigh carbon content and their molecules contain on the average at least.6 atom of carbon per atom of hydrogen, and are generally unsaturated,and may contain up to two unsaturated linkages per molecule. Thehydrocarbons may also contain an adventitious minor proportion ofsulphur and/r nitrogen in combined form.

We have now found that a treatment of the same hydrocarbon material byair blowing results in improvement in certain of the properties of thefinal polymer; and particularly the resistance to flexing at lowtemperature, of the resulting polyvinyl chloride compositions.

Mineral oil fractions, which term is intended to include mineral oilresidues, as hereinbefore described are first extracted with a selectivepolar solvent, which term is intended to include a mixture of selectivesolvents one at least of which is of a polar character. The desiredhydrocarbons are to be found in the extract phase and are recovered bythe removal of the solvent, advantageously by distillation. The extracthydrocarbons thus obtained are accordin to the present inventionair-blown at a moderately elevated 6 Claims. (Cl. 260-291) temperature,and the resulting material may then be incorporated in polyvinylchloride or co-polymer compositions as a filler or as a filler andplasticiser either alone or with known plasticisers.

The solvent extraction step may be carried out according to knownmethods. We have found that a mixture of sulphur dioxide and benzenegives successful results, but a wide range of other known solvents mayalso be advantageouslyused, as for example, sulphur dioxide, alcohols,furfural or phenols.

The air-blowing may be carried out for periods of from about 5 hours upto 50 hours or even long-. er at a temperature within the range to 300C., and preferably within the range to 250 C. The air-blowing may becarried out under superatmospheric pressure, but in general it isadvantageous to operate at atmospheric pressure.

The treated extract material may be processed in known manner, forexample by distillation, partial absorption on porous earths or similarmaterials, or precipitation with solvents or otherwise, with the objectof rendering the material lighter in colour, before its incorporationinto compositions as hereinbefore described.

The resulting compositions when the treated extract hydrocarbons areused as plasticisers and/ or fillers, or when incorporated with knownplasticisers show marked improvement in low temperature resistance ofthe resulting polyvinyl chloride compositions, as compared with thecompositions prepared in the use of extract hydrocarbons in accordancewith the process of the copending application Serial No. 513,468.lmprovement in electric properties may also result from the use ofair-blown material in place of untreate ed extract material, and byvarying the formulation, to take advantage of the improved lowtemperature flexibility, still further improvement in electricalproperties may result.

By varying the proportions in the final composition, it is also possibleto improve the electrical properties of the finished polyvinyl chlorider composition.

The following Examples 1, 3 and 5 illustrate the preparation of theair-blown material, for use properties resulting from the use ofair-blown, 1

material as against the untreated material.

Example 1.--A mineral oil fraction boilipg lin, the approximate range435-485 C. at 760.;-mm;=.=,. Hg pressure was submitted tomultiple-stage.

counter-current extraction with a. mixture of sulphur dioxide andbenzene in the ratio of 85 parts by vol. of sulphur dioxide to 15 partsby vol. of benzene employing atotal proportion of the mixture amountingto 200% by volume of the mineral oil fraction, and employing atemperature gradient during extraction or 140 to 25 F. The extracthydrocarbons after evaporation of benzol and sulphur dioxide amounted to30% by weight of the original mineral oil fraction'and had a specificgravity at 60 F. of 1.013.

The material prepared according to the method above described was heatedfor 8 hours at 195- 200 C. and a gentle stream of air passed through thematerial at atmospheric pressure, ensuring eflective distribution of theair stream. The product had a specific gravity at 60 F. of 1.028.

Example 2.-This example illustrates the improvement in low-temperatureflexibility obtained by the use of the treated instead of the untreatedextract hydrocarbons and at the same time shows that an improvement inelectrical loss factor may also be obtained.

25 parts by weight of the air-blown extract hydrocarbons preparedaccording to Example 1 were mixed with 100 parts by weight of polyvinylchloride, 25 parts by weight of dibutyl phthalate, 4 parts by weight oflead silicate and 2 parts by weight of ethyl palmitate in an internalmixer for 20 minutes at 120 C., after which the mixture was transferredto a roll mill and milled for 20 minutes at 140 C. The sheet ofplasticised material thus obtained was moulded under pressure at 150 C.to 0.05 inch thickness.

The properties of the composition so prepared are given -in thefollowing table in comparison with those of a product obtained in theuse of the untreated extract hydrocarbons.

Example 3.--A mineral oil fraction boiling in the approximate range435-485 C. at 760 mm. Hg pressure was submitted to multiple-stage,counter-current extraction with a mixture of sulphur dioxide and benzenein the ratio of 85 parts by volume of sulphur dioxide to parts by volumeof benzene, employing a total proportion of the mixture amounting to200% by volume of the mineral oil fraction and employing a temperaturegradient during extraction of 140 to 25 F. The material extracted, afterevaporation of benzol and sulphur dioxide, amounted to 30% by weight ofthe original mineral oil fraction and had a specific gravity at 60 F. of1.013. The material prepared according to the method described washeated for 24 hours at l95-200 C. and a gentle stream of air passedthrough the material at atmospheric pressure in such a manner thateffective distribution of the air stream was achieved. The product had aspecific gravity at 60 F. of 1.061.

Example 4.This example illustrates the improvement in electricalproperties which may result when air-blown material is employed in placeof untreated material.

Twenty-five parts by weight of the air-blown material prepared accordingto Example 3 were mixed with parts by weight of polyvinyl chloride, 25parts by weight of dibutyl phthalate, 4 parts by weight of lead silicateand 2 parts by weight of ethyl palmitate in an internal mixer for 20minutes at C. after which the mixture was transferred to a roll mill andmilled for 20 minutes at C. The sheet of plasticised material thusobtained was moulded under pressure at C. to 0.05 inch thickness. Theproperties of the composition so prepared are indicated in the followingtable in comparison with those of a product obtained in the use of theuntreated material:

Example 5.A mineral oil fraction boiling in the approximate range435-485 C. at 760 mm. Hg pressure was submitted to multiple-stagecounter-current extraction with a mixture of sulphur dioxide and benzenein the ratio of 85 parts by volume of sulphur dioxide to 15 parts byvolume of benzene, employing a tota1 proportion of the mixture amountingto 200% by volume of the mineral oil and employing a temperaturegradient; during extraction of 140 to 25 F. The material extracted,after evaporation of benzol and sulphur dioxide, amounted to 30% byweight of the original mineral oil fraction and had a specific gravityof 1.013. The material prepared as described was heated at -200 C. and agentle stream of air passed through the material at atmospheric pressurein such a manner that effective distribution of the air stream wasachieved. The treatment with air was continued until the specificgravity at 60 F. of the product was 1.027.

Example 6.-This exampl illustrates the improvement in electricalproperties which may be achieved by the use of air-blown material ratherthan the untreated hydrocarbon material when compounding is altered toutilise the superior low temperature flexibility of compositionscontaining air-blown material and indicates the properties of acomposition (I) containing 25 parts by weight of untreated hydrocarbonmaterial to each 100 parts by weight of polyvinyl chloride and 25 partsby weight of dibutyl phthalate in comparison with the properties of acomposition (II) containing 27.5 parts by weight of air-blown materialprepared as in Example 5 per 100 g. of polyvinyl chloride and 22.5 partsby weight of dibutylphthalate.

Determinations I Low Temperature Crack Point, C Volume Resistivity.ohm-cm Spegilc Inductive Capacity atc. p. s

800 c. p. S Loss Factor at o sou Es so We claim:

1. The composition or matter of improved low temperature flexibility andelectrical properties comprising an intimate admixture of a polymericsubstance selected from the group consisting of polyvinyl chloride,vinyl chloride-vinyl acetate co-polymer, vinyl chloride-methyl acrylateco-polymer and vinyl chloride-vinylidene chloride co-polymer and with anair-blown hydrocarbon material prepared by the air-blowing for aprolonged period of from about 5 hours up to 50 hours at a moderatelyelevated temperature within the range 150-300 C. of extract hydrocarbonsderived from a'mineral oil fraction by solvent extraction with aselective polar solvent, the extracted hydrocarbons containing up to twounsaturated linkages per molecule and having a carboncontent of onaverage at least .6 atom of carbon per atom of hydrogen, the molecularweight of the hydrocarbons being in the range of from about 200 to about800, and

the initial and final boiling points being in the range of from about250 C. to about 800 C. at 760 mm. Hg pressure.

2. The composition of matter as specified in claim 1 in which themolecular weight of the hydrocarbons is in the range of from about 250to about 750.

3. The composition of matter as specified in claim 1 in which the periodof air-blowing is from about 5 hours up to about 50 hours at atemperature within the range of from about 190 to about 250 C.

4. A process for the production of vinyl polymer plastic compositions ofimproved low temperature flexibility and improved electrical propertiescomprising intimately incorporating at an elevated temperature apolymeric substance selected from the group consisting of polyvinylchloride, vinyl chloride-vinyl acetate co-po1y- Iner, vinylchloride-methyl acrylate co-polymer initial and final boiling pointswithin the range 250-800 C. at 760m. of mercury pressure, containing upto two unsaturated linkages per molecule and having a carbon content ofon average at least 0.6 atom of carbon per atom of hydrogen, and byair-blowing the extracted hydrocarbons at a temperature within the range-300 C. for a period of from about 5 hours to about 50 hours.

5. A process of producing plastic compositions as specified in claim 4in which the air-blown hydrocarbons have been produced by air-blowingatta temperature within the range -250 C.

6. A process of producing plastic compositions as specified in claim 5in which the air-blown hydrocarbons are of molecular weight in the range250-750. 7

ERIC WILLIAM MUSTHER FAWCETT. ERIC SYLVESTER NARRACOT'I'. KATHLEEN JOANROWLAND.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED 'STATES PATENTS Number Name 'Date 2,217,988 Lawson et al. Oct.15. 1940 2,337,339 McCluer et a]. Dec. 21, 1943 2,350,007 Zerbe May 30,1944 FOREIGN PATENTS Number Country Date 562,956 Great Britain July 24,1944

